xpcom/io/nsIStreamBufferAccess.idl@97036ab72558
xpcom/io/nsIStreamBufferAccess.idl
Tue, 06 Jan 2015 21:39:09 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Tue, 06 Jan 2015 21:39:09 +0100
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
- permissions
- -rw-r--r--
Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 /* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 #include "nsISupports.idl"
8 /**
9 * An interface for access to a buffering stream implementation's underlying
10 * memory buffer.
11 *
12 * Stream implementations that QueryInterface to nsIStreamBufferAccess must
13 * ensure that all buffers are aligned on the most restrictive type size for
14 * the current architecture (e.g., sizeof(double) for RISCy CPUs). malloc(3)
15 * satisfies this requirement.
16 */
17 [scriptable, uuid(ac923b72-ac87-4892-ac7a-ca385d429435)]
18 interface nsIStreamBufferAccess : nsISupports
19 {
20 /**
21 * Get access to a contiguous, aligned run of bytes in the stream's buffer.
22 * Exactly one successful getBuffer call must occur before a putBuffer call
23 * taking the non-null pointer returned by the successful getBuffer.
24 *
25 * The run of bytes are the next bytes (modulo alignment padding) to read
26 * for an input stream, and the next bytes (modulo alignment padding) to
27 * store before (eventually) writing buffered data to an output stream.
28 * There can be space beyond this run of bytes in the buffer for further
29 * accesses before the fill or flush point is reached.
30 *
31 * @param aLength
32 * Count of contiguous bytes requested at the address A that satisfies
33 * (A & aAlignMask) == 0 in the buffer, starting from the current stream
34 * position, mapped to a buffer address B. The stream implementation
35 * must pad from B to A by skipping bytes (if input stream) or storing
36 * zero bytes (if output stream).
37 *
38 * @param aAlignMask
39 * Bit-mask computed by subtracting 1 from the power-of-two alignment
40 * modulus (e.g., 3 or sizeof(uint32_t)-1 for uint32_t alignment).
41 *
42 * @return
43 * The aligned pointer to aLength bytes in the buffer, or null if the
44 * buffer has no room for aLength bytes starting at the next address A
45 * after the current position that satisfies (A & aAlignMask) == 0.
46 */
47 [notxpcom,noscript] charPtr getBuffer(in uint32_t aLength, in uint32_t aAlignMask);
49 /**
50 * Relinquish access to the stream's buffer, filling if at end of an input
51 * buffer, flushing if completing an output buffer. After a getBuffer call
52 * that returns non-null, putBuffer must be called.
53 *
54 * @param aBuffer
55 * A non-null pointer returned by getBuffer on the same stream buffer
56 * access object.
57 *
58 * @param aLength
59 * The same count of contiguous bytes passed to the getBuffer call that
60 * returned aBuffer.
61 */
62 [notxpcom,noscript] void putBuffer(in charPtr aBuffer, in uint32_t aLength);
64 /**
65 * Disable and enable buffering on the stream implementing this interface.
66 * DisableBuffering flushes an output stream's buffer, and invalidates an
67 * input stream's buffer.
68 */
69 void disableBuffering();
70 void enableBuffering();
72 /**
73 * The underlying, unbuffered input or output stream.
74 */
75 readonly attribute nsISupports unbufferedStream;
76 };
78 %{C++
80 /**
81 * These macros get and put a buffer given either an sba parameter that may
82 * point to an object implementing nsIStreamBufferAccess, nsIObjectInputStream,
83 * or nsIObjectOutputStream.
84 */
85 #define NS_GET_BUFFER(sba,n,a) ((sba)->GetBuffer(n, a))
86 #define NS_PUT_BUFFER(sba,p,n) ((sba)->PutBuffer(p, n))
88 %}
